Simplified cathode ray tubes and guns therefor



Nov. 4, 1958 B. w. SQUIER, JR 2,859,366

SIMPLIFIED CATHODE' RAY TUBES AND GUNS THEREFOR Filed Jan. 4, 1956 2 Sheets-Sheet 1 HOP/201V 76L SW42? GQVIRA roe //vv/v7'0/? BE/PTIFANO m 500/672, .112.

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Afro/aver Nov. 4, 1958 B. w. SQUIER, JR 2,859,366

SIMPLIFIED CATHODE RAY TUBES AND GUNS THEREFOR Filed Jan. 4, 1956 2 Sheets-Sheet 2 1.4 TTO/PNEY magnetic field produced by a magnet, not shown. The anodes and 21 are also supported on the rods 18 by straps 24 and 25, respectively.

A focussing lens subassembly is mounted on the outer end of the anode 21. The first element of this lens system comprises a thimble-shaped piece of metal 26 formed with" a closed outer end 27 having a depressed central portion 28 formed with an opening 30 at the center, as best seen in the diagram of the focussing lens system in Fig. 5. A second element of this lens subassembly is formed as a metallic thimble 31. The inner closed end of this thimble has a central depressed region 33 with an aperture 34 at its center. The third lens element comprises a metallic sleeve 35 mounted concentrically about a space between the lens elements 26 and 31. The three lens elements are held in position by means of'three rods of insulating material 36 to which the elements are connected by lateral members 37. The lens elements are attached to the supporting rods 36 in a jig by a beading operation. This means that the jig must be alternately heated and cooled, causing distortion. The maintenance operation necessary to correct for this is expensive. The focussing lens system is supported by the inner member 26 being welded to the anodemember 21.

The outer lens element 31 is formed with an enlargement 38 at its outer end terminating in a flange 40 with fingers 41 formed integral with this flange. The fingers serve to support and center the gun assembly within the neck 13. The getter support structures 42 are attached to this flange 40. The lens elements 26 and 31 are electrically connected together by a conductor 31a, and to a source of positive potential 45 through the conductive coating 22 by means of the fingers 41. The central lens element 35 is connected to a source of less positive potential through a conductor 43. The resulting focussing field is represented in Fig. 5 by the lines 44 of equal potential.

The lens assembly is welded to the anode 21, while the parts are held in a jig. As the gun assembly is inserted in the neck 13 of the evelope 10, the fingers 41 come into contact with the neck and compress, exerting pressure on the gun assembly which has a tendency to distort it and force the lens elements out of alignment. It can also be seen that the neck must be considerably larger in diameter than necessary to accommodate the anode and focussing lens structures alone.

These ditficulties are overcome by the construction of the invention shown in Figs. 2, 3, 4, and 6. The references numeral designates generally the envelope with a face plate 111 coated on its inner surface with a phosphor screen 112 and having a neck 113. A gun is mounted in the neck 113.

This gun assembly consists of a cathode 114 within which is mounted a heater 115 connected to a source of heating energy by connectors 115a. The cathode is mounted in an apertured grid 116 attached to a'pair of insulating rods 117 mounted axially in the neck 113 on either side of the gun assembly. This grid 116 has applied to it the usual negative bias by means of a connector 118. There are three successive anodes 120, 121, and 122.. Anode 122 comprises a coating of conductive material on the inner surface of the neck 113 of the envelope 110. There is a biased slash 123 between the anodes and 121 to produce the so-called ion trap efiect. Other known constructions may be used to obtain this effect. The anodes 120 and 121 are also attached to the rods 117. The anode 121 is formed as a thimble with a closed outer end 127 having a depressed central portion 128 formed with an aperture 130 at the center, as best seen in Figs. 4, 5, and 7. The second element of the focussing lens is formed by the conductive coating 122 on the inside of the neck 113 that also serves as the third anode. The third element of the focussing lens comprises a metallic sleeve 131 maintained at a potential negative with respect to the anode 121 and the conductive coating 122 as indicated by the battery 132 in Figs. 4 and 6 connected by means of a conductor 133.

The gun assembly is positioned within the neck 113 and connected to the coating 122 by means of fingers 134 attached to the anode 121. The third focussing lens element 131 is supported on the rods 117 by means of rods 135 extended axially from the rods 117. These rods and conductor 133 are fastened to the sleeve 131' by being crimped into loops 136 and 137 formed in a band 138 of metal previously attached either by soldering or welding to merit 131. This attachment may be treated to remove burrs and other irregularities while still a separate part. The getter support 140 is attached to the anode 121, as shown in Fig. 3. As best seen in Fig. 5, a magnet 141 is applied for returning the electron beam indicated by the dotted lines 142 and 143 to the axis indicated by the dotted line 144. The electron beam 142 and 143 is subjected to the focussing effect of the lens elements 121, 131, and 122 to bring the beam to a virtual point on the phosphor screen 112. Deflection is accomplished by coils 145 and 146 supplied with suitable deflecting currents from horizontal. sweep generator 147 and vertical sweep generator 148, respectively. The signal for modulating the intensity of the light produced is applied at terminals 150 and 151 across a resistor 152 connected in series with a source 153 of biasing potential' between the grid 116 and the cathode 114. The first anode 124) is maintained at a positive potential with respect to the cathode 114 by means of a battery 154. The lens element 131 is maintained at-a positive potential with respect to the anode 120 by means ofa battery 155 to complete the electron lens system and give approximately the fields indicated by the lines 156 and 157, indicating the locus of points of equal potential. It will be noted that the lines 156 bend away from the apertured lens disc 121 until they assume the S shape of lines 157,

due to the asymmetry of the geometry of the lens system. The focussing eflFect is improved if the neck coating is carried back behind the focussing lens system.

It can be seen by a comparison of Figs. 1 and 2 that a more compact gunstructure is obtained with the construction of this invention. For example, while a neck diameter of 1 /2 inchesis requiredfor a representative cathode ray tube, a tube of the same performance characteristics can be constructed with the principles of this invention having a neck diameter of 1% inches. As pointed out above, this permits the use of a shorter tube or less power for the same deflection. When this gun is inserted into the neck'113, any distorting forces applied by the fingers 134 are applied to the sturdier anode 121 and not to the less securely fastened third lens assembly 131. Thus, there is no likelihood of distortion being introduced during the insertion of the gun into the neck. It will also be apparent by such comparison that a gun constructed according to the principles of this invention consists of fewer parts in that there is no separate outer lens element to be supported on the gun structure, nor are separate supporting rods needed for holding the focussing lens assembly in alignment. A further saving in parts is made by being able to form the first lens element integral with the second anode 121.

It is possible to utilize the neck coating as the centralfront by a similar insulating means for supporting said ring substantially as axial with said lens disc and extending beyond said lens disc in the desired direction of travel of the electron beam comprising at least one rod of insulating material with its axis parallel to the axis of said lens disc and ring, at least one laterally extending member connecting said lens disc to said insulating rod, an axially extending member connecting said lens ring to said insulating rod, and an envelope for said device having a neck with a conductive coating on the inside.

2. In a cathode ray device, an envelope having a neck with a conductive coating inside, an electrostatic focussing lens including an apertured disc, an annular lens ring, and insulating means for supporting said ring substantially coaxial with said lens disc and extending beyond said lens disc in the desired direction of travel of the electron beam comprising at least one rod of insulating material with its axis parallel to the axis of said lens disc and ring, at least one laterally extending member connecting said lens disc to said insulating rod, an axially extending member connecting said lens ring to said insulating rod, a band about said lens ring formed witha crimped loop to hold said axially extending member, and the conductive coating on the inside of the neck.

3. In a cathode ray device with a phosphor screen, a gun assembly structure comprising an electrostatic lens disc formed integral with a tubular accelerating electrode, an annular lens ring, insulating means for supporting said annular lens ring substantially coaxial with said lens disc so that it extends beyond said lens disc in the desired direction of travel of the electron beam comprising at least one rod of insulating material with its axis parallel to the axis of said lens disc and ring, at least one laterally extending member connecting said lens disc and accelerating electrode to said insulating rod, an axially extending member connecting said lens ring to said insulating rod, an envelope for said device having a neck with a conductive coating on the inside extending back from the screen at least as far as the outer end of the lens ring, and means for supporting said lens disc within said neck and electrically connecting it to said conductive coating.

4. In a cathode ray device with a phosphor screen, a gun assembly structure comprising an electrostatic lens disc formed integral with a tubular accelerating electrode, an annular lens ring, insulating means for supporting said lens ring substantially coaxial with said lens disc and extending beyond said lens disc in the desired direction of travel of the electron beam comprising at least one rod of insulating material with its axis parallel to the axis of said lens disc and ring, at least one laterally extending member connecting said lens disc and accelerating electrode to said insulating rod, an axially extending member connecting said lens ring to said insulating rod, a band about said lens ring formed with a crimped loop to hold said axially extending member, an envelope for said device having a neck with a conductive coating on the inside extending back from the screen at least as far as the outer end of the lens ring, and means for supporting said lens disc within said neck and electrically connecting it to said conductive coating.

5. An electron gun assembly for a cathode ray device comprising an electrostatic lens disc formed integral with a tubular accelerating electrode, an annular lens ring, insulating means for supporting said lens ring substantially coaxial with said lens disc and extending beyond said lens disc in the desired direction of travel of the electron beam comprising at least one rod of insulating material with its axis parallel to the axis of said lens disc and ring, at least one laterally extending member connecting said lens disc and accelerating electrode to said insulating rod, and an axially extending member connecting said lens ring to said insulating rod.

6. An electron gun assembly for a cathode ray device comprising an electrostatic lens disc, an annular lens ring, insulating means for supporting said lens ring substantially coaxial with said lens disc and extending beyond said lens disc in the desired direction of travel of the electron beam comprising at least one rod of insulating material with its axis parallel to the axis of said lens disc and ring, at least one laterally extending member connecting said lens disc to said insulating rod, an axially extending member connecting said lens ring to said insulating rod, and a band about said lens ring formed with a crimped loop to hold said axially extending member.

References Cited in the file of this patent UNITED STATES PATENTS 2,160,021 Iams May 30, 1939 2,219,111 Nicoll Oct. 22, 1940 2,225,901 Bruche Dec. 24, 1940 2,249,552 Zworykin July 15, 1941 2,638,559 Giacchetti May 12, 1953 2,656,481 Leighton Oct. 20, 1953 2,733,365 Hoagland Ian. 31, 1956 2,793,312 Hangen et a1. May 21, 1957 

